What Are the Odds That the Odds Are Incalculable?

LONDON(AP) A mixed-race British couple has defied the odds _ twice _ by producing two sets of twins in which one sibling appears to be black and the other white. Dean Durrant's newborn daughter Miya has dark skin like him. Twin sister Leah has fair skin like her blue-eyed, red-haired mother, Alison Spooner.

Their older siblings Lauren and Hayleigh, born in 2001, also have strikingly different skin tones and eye colors.

"There's no easy way to explain it all. I'm still in shock myself," Durrant, 33, told Sky News on Wednesday.

Both sets of twins are fraternal rather than identical, meaning they are the product of two separately fertilized eggs, so it is not unusual that they don't look alike. Miya's skin color was more influenced by her father's genes, while Leah takes after her mother.

But scientists say it's rare for a couple to have two sets of twins, end even rarer for them to have such different appearances.

"Even non-identical twins aren't that common," Dr. Sarah Jarvis of Britain's Royal College of General Practitioners told Sky. "Non-identical twins from mixed parents, of different races, less common still. To have two eggs fertilized and come out different colors, less common still. So, to have it happen twice must be one in millions."

The phenomenon is so uncommon that there are no statistics to illustrate its probability, although it is thought likely to become more common because of the growing number of mixed-race couples.

When asked to explain what it meant for the odds of a phenomenon to be incalculable, a British statistician at the Royal Institute of Nonsense Numbers, said the odds that he was going to visit his favorite pub after work for two pints of stout were 100%. "After I've 'ad me two pints the odds of when I'll arrive at me wee 'ome, are incalculable." The man refused to give his name, on condition of anonymity. But a quick Internet search of Institute employees revealed a statistician with the odd name of Oddly Odd.

The twins were born prematurely in November in Frimley, southern England, and spent several weeks in the hospital. They are now at home with their parents in Fleet, 40 miles (60 kilometers) southwest of London. Oddly enough, Fleet is over 98% black, Ms. Spooner's OBGYN is a black man and Mr. Durrant travels about half the year in connection with his employment. What are the odds?